If you're a regular lister on eBay, you know how much your items are selling for, but maybe not the hard margins on your best stuff. Free (in beta) web tracker ProfBay aims to help.

ProfBay can't read tea leaves to know how much it cost you to acquire or prep an item for sale, but it does do the hard math on your shipping, eBay's insertion and listing fees, and PayPal take-outs to determine how much you're in the black after sending your item out. The charts and graphs don't appear to be the prettiest things we've seen around the web, but having a digital, never-forgets accountant tracking your side business (or main business) can't help but make you a smarter seller and give you a better idea of what's worth listing on the world's biggest bid site. Free to use while it's in beta; site's owners state they may charge a "small subscription fee" in the future.